class MoreMath::Sequence

def detect_outliers(factor = 3.0, epsilon = 1E-5)

less than epsilon, nil is returned.
:median and :iqr parameters. If no outliers were found or the iqr is
:very_high outliers, determined by the box plotting algorithm run with
Return a result hash with the number of :very_low, :low, :high, and 
def detect_outliers(factor = 3.0, epsilon = 1E-5)
  half_factor = factor / 2.0
  quartile1 = percentile(25)
  quartile3 = percentile(75)
  iqr = quartile3 - quartile1
  iqr < epsilon and return
  result = @elements.inject(Hash.new(0)) do |h, t|
    extreme =
      case t
      when -Infinity..(quartile1 - factor * iqr)
        :very_low
      when (quartile1 - factor * iqr)..(quartile1 - half_factor * iqr)
        :low
      when (quartile1 + half_factor * iqr)..(quartile3 + factor * iqr)
        :high
      when (quartile3 + factor * iqr)..Infinity
        :very_high
      end and h[extreme] += 1
    h
  end
  unless result.empty?
    result[:median] = median
    result[:iqr] = iqr
    result[:factor] = factor
    result
  end
end